1. Field of the Invention
The invention relates in general to a method of fabricating electrode structures on a substrate, and more particularly to a method of improving output current and output voltage of a dye-sensitized solar cell (DSSC).
2. Description of the Related Art
Dye-sensitized solar cells (DSSC) have many advantages, such as low cost, high efficiency, easy fabrication and high plasticity. Further, Dye-sensitized solar cells (DSSC) can generate electric power with an indoor light source which is not limited by sunray incident angles. A standard dye-sensitized solar cell includes a substrate (glass substrate or thin film substrate), a transparent conductive film, a working electrode (including a semiconductor layer and dye), an electrolytic material (electrolyte), and an counter electrode coated with a transparent conductive film and a platinum catalyst on a substrate. Output efficiency of dye-sensitized solar cell module is only about 6-8% and output power is not high enough. Therefore, it is important to improve efficiency and output power of dye-sensitized solar cells.
Generally, patterned silver lines and passivation glues are formed on a conductive substrate using a screen printing method when fabricating sub-module cells of dye-sensitized solar cells. During the design process, a specific buffer space between the working electrode and the passivation glue is left, which reduces the active area of the sub-module working electrodes.
Electrophoretic deposition has many advantages. For example, electrophoretic deposition has a fast deposition rate and can be performed on any shape of conductive subject, and the equipment for electrophoretic deposition is simple to operate. Electrophoretic deposition comprises dispersing and suspending sol particles uniformly in a liquid according to control of a surface state of the sol particles, immersing two electrodes in a solution, applying a DC electric field between the two electrodes for the particles with charges moving toward the electrode having reverse electric characteristics. The particles are finally deposited on the substrate to form a film.
China pattern CN 1763261A discloses electrophoretic depositing a TiO2 film using cyclic voltammetry on a glass conductive substrate. The conductive substrate with an electrode structure can be used on dye-sensitized solar cells. However, the conventional electrophoretic deposition method has many limits. For example, cyclic voltammetry is required when fabricating TiO2 electrodes. Therefore, deposition of the cathode in an electrophoretic tank is limited. An electrophoretic liquid must comprise a salt electrolyte and an electrode is required to be treated using a micro wave of under 400-500° C. An electrode with desired quality cannot be obtained merely using electrophoretic deposition.